Xfinity router have a inbuilt troubleshooting program which ensures it can handle some bugs but here are some quick fixes for manually fixing Xfinity Wi-Fi not working. Restart your modem through My Account online, go to the internet service tab, and scroll down to devices and select restart modem. Start troubleshooting which can take up to ten minutes. After restarting make sure your device is plugged in properly to a power source. Ensure your account updated. Try moving closer to the router for better connectivity.